Telephone system and apparatus



(No Model.)

I. H. PARNHAM.

TELBPHONE SYSTEM AND APPARATVUS.

No. 281,478. Patented July 17, 1883.

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UNITED STATES -PAT NT OFFICE;

ISAIAH H. FARNHAM, OF PORTLAND, MAINE.

TELEPHONE SYSTEM AND APPARATUS.

SPECIFICATION forming part of Letters Patent No. 281,478, dated July 17, 1883.

Application filed April 2, !8:3.

To all whom it may cancer-n,.-

Be it knownthat I, I. H. FARNHAM, of Portland, in the county of Cumberland and State of Maine, have -invented certain Improvements in Telephone Central- Office Systems and Apparatus, of which the following is a specification.

My invention relates to telephone-exchange systems, and more especially to certain special organizations, arrangements, and devices' whereby the manipulations of the central offiee may be performed with increased celerity and certainty, and whereby the noise and confusion inseparable from such manipulations are materially diminished.

The specific aim of my invention is to provide increased facilities for the interconnection of Subscribers* lines, especially when such lines enter the central station upon different switch-board sections, and also to provide suitable indicating devices, whereby, when a connecting bar or line common to all of the switch-sections is in use by any one of the said switch-sections, the fact may be at once indicated to all, the indication of such use continuing so long as the use of the conecting-bar continues, and ceasing upon the discontinuance thereof.

It has been found very convenient in large telephone exchanges to divide the entering lines into groups of any desired number, each of the said groups being connected with a separate section of switch-board and assigned to the care of an operator. It is furthermore customary to provide each of the said switchsections with a complete outfit of switching, signal receiving and'transmitting, and supervising apparatus, so that as long as the substations connected with any one section desire only to communicate with other sub-stations connected with the same section each switchsection is practically an exchange organization complete in itself. It is evident, however, that as' the aggregate number of Subscribers connected with the other switch-sections must greatly preponderate over those of any one section the great majority of i communications will be with sub-stations connected with other switch-sections. Connecting devices are therefore essential which eXtend from each board to every other board, and these may, and gen erally (No model.)

do, assume the form of metal bars or strips eX- tending transversely across the several switchboards, and connected with the corresponding connecting-bars of other boards by suitable wires, although they may, when desired, simply be socket-plates similarly connected, in which case they are united with the line-wires by fiexible cords and plugs. A definite number of these connecting bars or plates are assigned exclusively for the local work of each switch-section-that is, if any sub-station on any board calls for another sub-station on the same board, these local bars are used. Consequently they begin and end on their own board, and have no connection with the connection-bars of other boards. For interconnection between the different boards, other bars are assigned, and upon each board a certain number of bars are united with a corresponding number upon every other board. Thus the switch-board A, besides being provided, for example, with ten local connectionbars, may also be provided with four connection-bars to switch-board B, four more to C, and so on, ad Z'b'tum, each other switch-board in the exchange-office being arranged on a similar plan. Expericnce has proved that the number of connecting-bars between any two boards must be kept at a very low limit, as otherwise the boards will assume such bulky and unwieldy proportions as to be unmanageable. On this account the number of bars between board and board does not ordinarily eX- ceed four. Yet it is also obvious that this defect or disadvantage is one which must rapidly increase as the Subscribers lines and the number of sectional switch-boards increase, and that, furthermore, 'even when as many as four connecting-bars are allowed between each two boards, circumstances must frequently occur when a greater number thanfour become absolutely, although temporarily, necessary, with IOO each other sectional switch-board-that is, one series from each board to every other boardof a third series common to and extending between all of the switch-boards.

It consists, secondly, in the conbination, with a series of connecting-bars common to and extending between all of a number of switch-boards, of a series of circuit-closers and indicating-annunciators at each switch-board, whereby the use of any of the said extra connecting-bars at any one of the switch-boards may be istantly indicatcd to each and all of the other switch-boards.

- It consists, thirdly, in certain arrangements of the circuits and circuit-closers with refercnce to the said connccting-bars, whereby the act of employing the connection-bar is caused to automatically actuate the circuit-closer of the indicator-circuit appertaining to the said bar.

It consists, fourthly, in a specific construction of the indicating-annunciators which I enploy, whcrcby a greater degree of sensitiveness is attained, and whereby I am enabled to operatc cfliciently a considcrable number of annunciators in and upon the same circuit. v

It consists, finally, in certain details of construction and arrangement which will be hereina'fter described, and which will be more specifically sct forth in the claims at the end of this specification.

In the drawings which aecompany and form a part of this specification, Figurc 1 is a diagrammatical representation of a series of four seetional switch-boards in a telephone central office, the whole being provided with connecting-bars common to all, and with devices to indicate their use in accordance with the terns of my invention. Fig. 2 is a sectional side elevation of the form of annunciator which I prefer. Fig. 3 is a front elevation of the same. Fig. 4 shows a detail illustrating the automatic operation of my invention, taken on the lineg y of Fig. 5, and Fig. 5, another detail of the same, the movable portion of the circuit-closer being hung from a suitable support, and capable of being operated from any part of the sectional switch-board.

In Fig. l, A, B, O, and D represent the different sectional switch-boards, which may be at any convenient distance from one another. Since the different subscribers lines have no specific relation to my invention, they are not shown.

As hereinbefore indicated, I provide connecting bars or strips of three different characters: first, bars for local connections, these being reprcsented by the bars a; second, separate series of bars from each switch-board to each other switch board. In the dr( wings these are represcnted by b. It will be observed that I have in the said drawings, for greater clearness, carricd out the connections in the board A only. I have, moreovcr, only shown one strip or bar connecting with board B, one with C, and one with D, wlereas in practice several bars of each board would be so connected. The principle, however, is the same, the difference being only in degree. A third series of connecting-'bars, c, are shown as extending throughout all the switch-boards from A to D, and irrespective of the number of the said boards. These bars, which are the only ones which are common to all the boards, and which are capable of being used by all of them, are to be used as a medium of communication between any two switch-boards only when all the others between the said two boards are already occupied. Any desired number of these common connecting-bars may of course be used. It now becomes necessary that when any of the common comecting-bars are in use between any two switch-boards the other switch-boards shall be notified of such occupation, in order that they shall not attempt a duplicate Occupation of the same, which would of course be equivalent to a cross or contact between the several line-wi res concerned. For this purpose I provide each sectional switchboard with a series of annunciators, g, equal in number to the common comecting-bars. In the drawings, as I have shown three of the said bars and numbered them l, 2, and 3, so I also have shown three annunciators at each board, and have designated them as g', 3/ and q'i At each switch-board I also place a series of circuit-closers, each consisting of a buttonswitch, c, and contact piece or studf therefor. These also correspond to the several common connecting -bars, and are consequently designated, respectively, c', c' and c, and f f and f All of the button-switch pivots at each switch-board are united and connected with ground-wires 1, 2, 3, and 4.

E is a voltaic battery or other source of current electricity, grounded at one of its poles and united at the other with a wire, 71, which divides into three branches, 10, 9, and 8. The branch 10 passes through the electro-magnet of the amnmciators g' of the switch-boards A, B, C, and D, successivcly, and, after passing through the coils of the last amunciator, returns by the wire 5 to the stud f at the board A, the said stud forming a nornally-open terminal therefor. It also touches or is branched into electrical connection with the stud f at all of the switch-boards. The branch batterywire 9 also passes suecessively through the helices of the amnnciators (1 of A B U, and returns by wire 6 to the stud f 2 at each, touching en routc all the studsj. The branch battery-wirc 8 in like manner includes all the annunciator-magnets f, and returns by wire 7 to the studf at A, touching en routc at the studs f at all of the switch-boards. Thus for each of the common connccting-bars l, 2, and 3, I provide an annunciator and means for closing the circuit of the same at each sectional switch-board. The several annunciators may, if desired, when actuated, show a number or any other prearranged devicc to indicate the special connecting-bar which they represent; or it may be understood that the IIO upper annunciator represents always the up per bar, the second indicator the second bar,

and so on.

In the operation of my invention letit be supposed that a line entering the board A is to be placed in communication with a line entering at D, and that all the special connecting-bars between A and D are already occupied. It is therefore necessary to use one of the through connecting-bars, which is accordingly done; but as the same contingency is at any time likely to arise between any other two boards, as soon as the connection is made the operator at A,who has employed the connecting-bar 1, now turns his littleswitch-button e' onto the stud f thus completing the batterycircuit through all the annunciators g' which correspond to that bar, the said annunciators thereupon becoming operative, and indi-` cating to all switch-boards that connecting-bar 1 is in use, and is thus blocked, and may not be used by any other operator until the blocksignal is Withdrawn. When the connectingbar is once more at liberty, it is the duty of the operator, who has blocked it by the indicatingsignal to turn his button-switch back immediately, which opens the circuit and withdraws the indicating-signals. Of course, if the connecting-bar No. 2is used, the annunciators g will also be employed, and in like manner the cireuit-closers and annunciators employed will invariably correspond with the number of the connecting-bar used. The form of annunciator which I have found to be most convenient, and which I prefer to employ, is that which is shown in Figs. 2 and 3. It is specially adapted for use in this combination by reason of the facility with which it withdraws the sigual when the circuit is opened; The Construction of this annunciator is as fo1-' lows, although it may be greatly varied without departi ng from the principle enployed:

A suitable case, F, is fitted with a glass front, z', and a short distance therefrom a steel needle, j magnetized either. permanently or by induction, is delicately pvoted in a plate of brass, k, or other suitable support. Immediately behind, the said support is an ordinary electro-magnet, M, which, by means of a screw,

p, working in a threaded chamber, n, fitted to the rear partition, m, is capable of adjustment to and from the needle. The end of the screwspindlep may be made to turn somewhat loosely in the block Z, so 'that the back and forward adjustment shall not tend to produce a rotary movement of the electro-magnet. The battery Operating the indicators may sometimes Weaken and fail to produce a deflection of the needle square across the face of its aperture or window. Moreover, if it appear desirable, for uniformity of appearance, to bring all the needles to a particular point on the dial, this may be effected in either case by providing a rotaryadjustment for the electro-magnet, whereby it is enabled to act more or less powerfully on the said needle. The electro-nagnet may thus be turned on its aXis, as shown in dotted lines in Fig. 3, (which is a section taken on the line z z of Fig. 2,) by loosening the lock nut o, and then turning the chamber n bodily in the recess of the partition m. The needle may also be slightly weighted, if necessary, at its lower end; but this will not usually be requisite, and I do not prefer it, as the sensitiveness of the annunciator is thereby impaired. By the use of this annunciator I am enabled to operate the hereinbeforedescribed signaling system in connection with a large number of switch-boards, using a comparatively small battery-power. I do not, however, restrict myself to its use, as in some cases I may find it convenient to use other forms. I have also devised means whereby the blocksignal may be operated automatically by the same movement that is made to connect any two lines together. This modification is represented in Figs. 4 and 5. V

In Fig. 4, G is a section of the switch-board, and the connecting-bars q are shown in section thereon. These are perforated at suitable distances apart by plug-holes r.

s s represent the incoming line, which eX- pands into a kind of spring-jack, s adapted to make contact, as shown, with the plug P. The circuit-closers are fixed immediately behind the plug-holes, and may consist, as shown, of an insulating-support carrying a series of contact -springs, x, one for each plug -hole, while the complementary contact is furnished by the pvoted plate w, which may stretch across the entire' switch-board section, so as to be operated by any or all of the plugs of the individual connecting-bars employed. A piece of non-conducting material, w is let into the said plate w opposite each plug, whereby the circuit-closing apparatus and indicating-circuit are completely insulated from the line-circuits. The pvoted plate'w is Suspended by the hangers c, and by means of the wire 10 is connected with the ground-wire, as shown in the manual circuit-closer Fig. l. The circuitsprings, bymeansof the wire 11., lead to the annunciators belonging to their special connecting-bar, and thence to the battery. I may of course substitute a metallic for a ground signaling-circuit, and the same Would in some IOO cases be preferred; or I may, if I prefer, utiladvisable, as it is liable to produce confusion between the main and the indicating circuits.

I am aware that heretofore signaling-circuits i have been arrc nged between the different sectional switch-boards of a telephone central .of-` fice; but they have uniformly been for the purpose of communication between the different operators, and have been adapted to produce transient signals only. On the contrary, my

oinvention contemplates the establishment of a block-signal to be maintained during the entire time that the common connecting-bars are` in use, and is intended, moreover, to subserve the purpose of an indieating-signal, and not in anyway to aid in communicating between the operators.

I make no claim herein to an annunciator of the special character described-name]y, an annunciator consistin of an electro-magnet capable of horizontal and rotary adjustment, and provided with a magnetic and polarized needle pivoted in front 01' or between the poles of the electro-nngnet, since 1 reserve the same to form the subject-matter of a separate application for Letters Patent.

Having now fully described my inrention, I claim-- 1. The combination,in atelephone-exchange system in which the incoming lines are grouped upon separate sectional switch-boards, oi' a series of local connection bars or pl ates, whereby any line maybe united to any otherline eutering at thesame switch-board, a number of series of interconneetion bars or plates extending between the difl`erent switch-boards, (one series ot' the number between each two of the said switch-boards,) whereby a line entering at any switch-board may be connected with a line at any other specific switch-board, and a series of through-connection bars or piates common to and extending successively and serially to each and all ot' the switch-boards, whereby lines entering at any two difl'erent switchboards may be connected when all of the bars extending exelusively between the said switchboards are occupied, substantially as described.

2. The eombinationinatelephone-exchange system of the character hereinbetbre specified, ot' a series of local comection-bars, a number ol' series ot' intereonneetion-bars,whereby each switch-board is independently connected with each other switch-board, a series of through eonneetingbars, each bar extending to all and adapted to be used by all ol' the said switchboards, and means, as specified, whereby the use ol' the common or through eonnecting-bars by any two of the switch-boards is indieated to all of the other switch-boards, substantially as described, and for the purposes set l'orth.

3. The combination,inatelephone-exchange system of the character specified, of a series of local connection-bars, a number of series of intereonnection-bars, each two switch-boards being independently connected by a single series, a series of through connecting-bars connecting with all and adapted to be used by all ot' the said switch-boards, and means, as indieated, whereby the use ot' the through conneeting-bars by any two oi' the switch-boards may be signaled to all of the other switchboards, and whereby, when the said use is discontinued, the signal indieating the same is automatically withdrawn, substantially as described.

4. In a telephone-exchange system in which the subscribcrs lines are grouped upon a number of separate and independent switch-boards, the combination of aseries of eonneeting-bars,

or their equivalents, eXtending to and between all of the said switch-boards and common to all, with a series of indicating-circuits, (one for each of the said conneeting-bars,) each of the said circuits being provided at each and all of the switch-boards with a cireuit-closer and an annunciator or indieator, whereby when any of the connecting-bars are in use between auytwo of the switch-boards the same may be indicated to all of the other switchhoards by elosing the indieating-eircuit of the said bar, the discontinuance of the said usebeing correspondingly indicated by opening the said cireuit, as described.

5. The combination, in atelephone-exchange system, oi' a series ot'sectional switch-boards, each adapted for the reception of a definite number ot' entering line-wires, with a series ol' eonneeting-hars extending to and between all of the said switch-boards, a series ol' indicating-circuits therei'or, one for each through conneeting-bar, each indicating-circuit being provided at each switch-board ol' the system with an indicator and a cireuit-Closer, whereby the use o',any of the counecting -bars by any switch-board may be indicated simultaneousl y to all of the others, and a battery connnon to all of the indieating-cireuits, substantially as specified.

(3. The combination, in atelephone-exchange system, of a series of sectioal switch-boards and a series ot' connecting-bars common to all of the said switch-boards, with a series ol' indieating-cireuits therefor, (one for each of the said connecting-bars,) each of the said cireu-its extending from abattery successively through a series of indicators or annunciators, one at each switch-board, and then branching toeach of a series of contact points, one at each switch-board, and terminating in a normallyopen condition at the last of the said contactpoints, and at each switch-board a series oi' cireuit-closing buttons or springs permanent] y united with ground-wires or with a return bat tery-wire, whereby, when any of the common. eonnecting-bars are in use by any of theswitchboards, the same may be indicated to the others by closing the corresponding indicatingcireuit through all ol' the annunciators thereof by means oi' any of the said eireuit-closers, as described.

7. The conbination of a series of sectional switch-boards and a series of eonneeting-bars common to all ot' the said switch-boards, with a series of indieating-circuits therefor, one for each of the said conneeting-bars, an annuneiator at each of the said switch-boards included in each imlicating-circuit, and automatic circnit-elosing devices, substantially as indicated, whereby the insertion of a connecting-plug in any ot' the said connecting-bars is automatically adapted to close the idicatingcireuit and give the occupation-signal to all of the other boards, as specified, and i'or the purposes described.

S. The combination of a series of connect- IOO ing-bars extendingbetween &number of switchboards and common to all of the said switchboards, with a series "of indicating-circuits therefo', one for each bar, a polarized annunciator at' each of the said switch-boards included in each indicatzg-circuit, and a series of circitclosers, one for each circuit, at each switch-board, as described.

9; The combination of a series of switchboard connecting-bars with indicating-circuits therefor, one for each bar, and automatic circut-closers located in the real' of the connecting-bars, and adapted to be operated by the insertion of a plug in the said connecting-ba3 as described.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 29th day of March, A. D. 1883.

ISA IAH HENRY FARNHAM.

e Witnesses:

FRANK S. WATERHoUsE, NATHAN GooMBs. 

